1. Field of the Invention
This invention relates to an agglutination judgment method for automatically judging the agglutination or non-agglutination of particles. In particular, this invention relates to a method of automatically judging the agglutination or non-agglutination of particles by optically measuring a reaction pattern of particles created in a vessel in a clinical test for instance.
2. Description of the Related Art
For the purpose of determining blood type or detecting antigens and antibodies in blood, a method of observing the agglutination of particles is generally used. In this method, blood specimen is dispensed in a reaction vessel and reagent particles are reacted immunologically. From the reaction pattern of the particles created on the bottom of the vessel, it is judged whether the agglutination of the particles occurs or not.
In recent years, this judgment has been mechanically performed. For example, the two-dimensional image of the particle agglutination is taken and the image data subjected to predetermined image processing. From the results of this processing, the agglutination reaction pattern of particles is judged (for example, see Japanese Patent No. 2525487).
However, this automatic judgment technique is accompanied with the problem that it is difficult to detect a weak positive image created by partial agglutination of particles. Herein, the partial agglutination means an agglutination reaction may be brought about in a blood typing test. Generally, the red blood cells which are not agglutinated are allowed to sediment at a central portion of the reaction vessel, thereby forming a “negative image”, i.e., a non-agglutinated image. However, if red blood cells differing in antigenicity are mixed with antibody capable of reacting with only one antigenicity of red blood cells, a partially agglutinated image wherein agglutinated red blood cells are mixed with un-agglutinated blood can be formed.
In this partial agglutination, although sedimentation can be observed at a central portion just like the ordinary negative image, agglutinated red blood cells are allowed to exist at the peripheral portion. Although it is possible to easily recognize these agglutinated red blood cells formed at the peripheral portion by visual inspection, this image of agglutinated red blood cells has been judged as negative in the case of the conventional automatic judgment. Therefore, even in the automatic agglutination judgment method, it has been conventionally required to correct the result by visual inspection by the operator, etc.